Injection moulds exist which are equipped for manufacturing disc-shaped articles with a central hole. Examples of this are compact discs, VLPs, laser discs and other information carriers. Such known moulds are of the two-part type and bound in closed position a disc-shaped mould cavity. After the injection moulding treatment the central hole is removed from the formed article by means of a punching process.
The drawback to this known art is that in this way valuable plastic is lost and that the quality of the hole is greatly dependent on the accuracy with which the punching process is performed, in particular the moment during the manufacturing cycle at which the actual punching takes place.